After announcing its intention last month to roll back emissions standards that require cars to get higher fuel economy, the EPA is now circulating a proposal in Washington to freeze the standards at 2020 levels through 2026.

The story was first reported by the Los Angeles Times, and confirmed by Reuters.

The proposal so far is a draft, which officials at the EPA and the NHTSA are discussing among others. Officials briefed on the proposal, however, say it is the leading recommendation.

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EPA spokesperson Liz Bowman declined to comment on the details of the draft plan.

"The Agency is continuing to work with NHTSA to develop a joint proposed rule and is looking forward to the interagency process," she wrote in an email to the Los Angeles Times. 

Rather than continue to ratchet standards up to 54.5 mpg by 2025, as the current law requires, the new proposal would stall out fuel economy increases at just short of 42 mpg in 2020, and hold them there through 2026.

If implemented, the ruling would put the federal government on a legal collision course with California, which is a party to the current standards and has proposed ratcheting up its standards, rather than loosening them.

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California has special rights to set its own emissions rules because the state began regulating emissions from cars before the EPA was formed.

Under the 1970 Clean Air Act, only California—which has climate and emissions challenges unique in the country due to its topography, location, and population—can set emissions standards tougher than the rest of the United States. Other states can choose to follow California's tougher standards, as 12 others do, or to follow the more relaxed federal standards.

However, to set standards tougher than federal levels, California has to obtain a waiver from the EPA.

EPA administrator Scott Pruitt [photo from 2014]

EPA administrator Scott Pruitt [photo from 2014]

The draft proposal under consideration would assert that a 1975 law setting fuel economy standards under the National Highway Traffic Safety Administration (NHTSA) pre-empts the California waiver—supporting EPA Administrator Scott Priutt's claim in Congressional testimony that he doesn't plan to revoke the waiver. Under the new draft proposal, he wouldn't have to, but would circumvent it legally instead.

The three agencies—NHTSA, EPA, and the California Air Resources Board—are involved because the Supreme Court ruled in 2007 that carbon dioxide, the most common greenhouse gas, is a pollutant that the EPA is required to regulate. Unlike smog forming emissions from internal combustion engines, such as unburned hydrocarbons and oxides of nitrogen, carbon dioxide can only be reduced by burning less gas—by statute the purview of NHTSA.

After President Obama took office, he ordered the three agencies to get together and coordinate fuel economy standards to limit CO2 emissions. That effort led to the current 54.5 mpg target by 2025 that the Trump Administration has said it intends to roll back.

Mary Nichols, chief, California Air Resources Board

Mary Nichols, chief, California Air Resources Board

California, meanwhile, has suggested it may follow China's lead in moving to ban internal combustion cars in the state altogether in the next decade, according to a Bloomberg report. Banning tailpipes could theoretically fall outside of emissions and fuel economy requirements.

Automakers have lobbied for lower fuel economy and emissions standards, as more buyers turn to trucks and SUVs, which they say makes the standards more difficult to meet. In conversations with the Trump Administration, however, they have also insisted that they do not want to set up a battle with California that could result in having to sell different cars in the state than they do elsewhere in the country.

With this proposal, a protracted legal battle seems practically inevitable.